The invention is directed to a bearing seal for the outer and inner blade angle bearings of the rotor hub of a rotary wing aircraft, comprising a lubricating oil chamber interconnecting the two bearings and connected to a device for replenishing lubricating oil, and a sealing ring arranged on that side of each of the bearings facing away from the lubricating oil chamber.
Known sealing arrangements for lubricants for the blade angle bearings of helicopter rotors utilize either a grease or an oil lubrication.
Grease lubrication has the disadvantage that the lubricating grease under the effect of the centrifugal force of the rotating rotor hub is separated into its components of different specific gravity and thus quickly loses its ability to lubricate, so that lubricating has to be repeated often in order to press the exhausted grease from the bearing chambers to the exterior and to replace it by a new grease filling.
These difficulties do not present themselves in known bearing seals of the kind mentioned at the beginning which utilize oil lubrication, since lubricating oils are not separated under the centrifugal force effect of the rotor, only the unavoidable relatively minor losses due to leakage at the sealing rings having to be replaced from the lubricating oil chamber extending between the two bearing chambers, or from a replenishing device. Here, however, heavy dirt particles, in particular, metallic shavings, present in the lubricating oil are centrifugally separated from the inner blade angle bearing and the lubricating oil chamber into the outer bearing causing heavy soiling and premature wear of the bearing races and of the sealing ring sealing the bearing chamber of the outer roller or sliding bearing to the exterior.